DAB MCE-55/P, Instruction For Installation And Maintenance

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4.4.1 Assigning the start-up order
Each time the system is activated, each inverter is associated a starting order. This setting establishes the
order of inverter start-up.
The starting order is modified during use according to requirements, by the two following algorithms:

Reaching of maximum operating time

Reaching of maximum inactivity time
4.4.1.1 Maximum operating time
According to parameter ET (maximum operating time), each inverter has an hour counter, and the starting
order is updated on the basis of these values according to the following algorithm:
- if at least half of the value ET is exceeded, priority is changed on the first shutdown of the inverter
(switch to standby).
- if the value ET is reached without stopping, the inverter stops unconditionally and this sets to the
minimum restart priority (switch during operation).
See ET: Tempo di scambio par 6.6.9.
4.4.1.2 Reaching of maximum inactivity time
The multi inverter system has an anti-stagnant algorithm that is aimed at maintaining pump efficiency and
integrity of the pumped liquid. It acts by enabling rotation of the pump starting order to ensure a delivery to all
pumps of at least one minute of flow every 23 hours. This is implemented regardless of the inverter
configuration (enabled or reserve). Priority switch envisages that the inverter stationary for 23 hours is set to
maximum priority in the starting order. This means that it is the first to be started up as soon as flow delivery
is required. The inverters configured as reserve have priority over the others. The algorithm terminates action
when the inverter has delivered at least one minute of flow.
After the anti-stagnant interval, if the inverter is configured as reserve, it is set to minimum priority to avoid
premature wear.
4.4.2 Reserves and number of inverters involved in pumping
The multi inverter system reads how many elements are connected in communicating mode and calls this
number N.
Then, on the basis of parameters NA and NC it decides how many and which inverters must work at a given
time. NA represents the number of inverters involved in pumping NC represents the maximum number of
inverters that can run simultaneously.
In a series, if there are NA active inverters and NC simultaneous inverters, when NC is less than NA, this
means that a maximum of NC inverters will start up simultaneously, and these will switch between NA
elements. If an inverter is configured with reserve priority, it will set as last in the starting order, therefore for
example, if there are 3 inverters and one of these is configured as reserve, the reserve unit will start in third
place; otherwise if set to NA=2 the reserve will not start up unless one of the two active units sets to fault
status.
See also the explanation of parameters
NA: Inverter attivi par. 6.6.8.1;
NC: Inverter contemporanei par. 6.6.8.2;
IC: Configurazione della riserva 6.6.8.3.